#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
	int n,k;
	cin>>n>>k;
	int t = 240;
	t = 240-k;
	int ans  = 0;
	int i = 1;
	do
	{
		//printf("****\n");
		if(t-i*5>=0) ans++;
		t = t-i*5;
		i++;
	}while(t>0);
	cout<<min(ans,n)<<endl;
}
